I have seen the chalkboard technique on several blogs lately. You start with a piece of black cardstock-most of the blogs I have seen stamp with either versamark or white craft ink then emboss with white embossing powder. You have to work fast doing it this way and I would recommend using your embossing buddy and embossing as you go.Otherwise the ink dries fast and you have to start over. I decided to skip embossing and just stamp with the white craft ink. I think it looks great this way and I was able to use multiple stamps from different sets. I used a white watercolour pencil for the edge and smudged a bit of ink in the gaps for a chalky effect. The party banner I stamped first, then cut it out and applied with Stampin dimensionals. If you choose to go in this direction make sure that you wait for the ink to dry thoroughly.
For more chalkboard ideas, visit this site: http://scrapbookgirl.typepad.com/paper_scissors_and_superh/2012/11chalkboard-art-meets-stamping.html